Hi Diana,
There isn't a function to transpose a region on the Mac version.

You could do it as follows though (for chords)

e.g. assume that you want to transpose 8 bars from 9-17 from Eb to F

1. tranpose the whole song to F
2. select the 8 bars and choose Copy (Command C)
3. Edit-Undo (Command Z) so that the whole song is Eb again
4. Paste (Command V) at bar 9

Have Fun!
Peter Gannon
PG Music Inc.